1. Field of the Invention
The present invention generally relates to a magnetic head used in reproducing a signal magnetic field from a magnetic recording medium such as a hard disk, and, more particularly, to a magnetic head of a type which induces the signal magnetic field to a magnetoresistance film by utilizing a magnetic guidance path (hereinafter referred to as a flux guide) guiding the signal magnetic field.
2. Description of the Related Art
A magnetic head of a magnetoresistance type (hereinbelow referred to as an MR head) is a reproducing head using a magnetoresistance film (hereinbelow referred to as an MR film). A reproduction by the MR head does not depend on a relative speed between the MR head and a magnetic recording medium such as a magnetic disk. Therefore, the MR head is widely employed as a magnetic head which contributes to intensifying a recording density of a magnetic recording device and miniaturizing a magnetic recording device.
Recently, however, as such a magnetic recording device has come to have a mass capacity with a high recording density, a bit length and a track width on a magnetic recording medium have been sharply becoming small and narrow. Accordingly, a signal magnetic field from the magnetic recording medium has been reducing; therefore, the MR head for reproduction is needed to be more sensitive.
In order to provide the MR head with a higher sensitivity, magnetic domains of the MR film need to be aligned so as to form a single magnetic domain. If the magnetic domains of the MR film fail to be aligned sufficiently into a single magnetic domain, a Barkhausen noise occurs so as to greatly fluctuate the output being reproduced. To tackle this problem, the MR film is provided with a magnetic-domain regulating film to regulate a magnetic domain of the MR film. It is known that such a highly coercive-force film as CoPt or such an antiferromagnetic film as PdPtMn can be used as the magnetic-domain regulating film.
In addition, a CPP structure has been proposed as one of structures that are designed to provide the MR head with a higher sensitivity, in which CPP structure an electric current flows in the direction of thickness of the MR film so as to achieve a great resistance change.
Besides, as a magnetic recording device has come to have a higher recording density, an MR circuit has been becoming finer and finer. In this trend, a conventional process of directly polishing the MR circuit inevitably has a limitation in terms of accuracy, which makes it difficult to produce the MR circuit with a good yield rate. To tackle this problem, it has been proposed that a magnetic head be provided with a flux guide so that the MR circuit is not directly polished.
The heretofore-mentioned techniques to provide the MR head with a higher sensitivity can be combined to produce a further preferable magnetic head.
However, when the above-mentioned flux guide has multiple magnetic domains, magnetic movements occurring in these magnetic domains are transmitted to the MR film, since a signal magnetic field from a magnetic recording medium first passes this flux guide. This causes a problem that, even if magnetic domains of the MR film themselves are sufficiently regulated, a Barkhausen noise occurs so as to inhibit a good reproduction.